Hi Team,
You might already have come across this stuff many a times.
I am sending this query as to why LVM is not supporting online shrink.
How is that AIX can do the shrink but not in our best Linux.
Is there a big difference i the underlying architecture which prevents us from
an online shrink?

You are asking this question on a wrong mailing list.
LVM2 of course does fully support online device shrink.
The other side of story is - there is no filesystem I'd know about which
would be supporting online shrinking. The fact is - it's pretty hard

Except for btrfs - which on the other hand doesn't need lvm2.
So if you need something shrinkable online - try to go with btrfs.
Zdenek